1. Field of the Invention
The present invention relates to a color filter manufacturing method and apparatus for manufacturing a color filter by discharging inks onto a substrate using ink-jet heads and coloring each pixel of the color filter, a color filter, a display device, and an apparatus having the display device.
2. Description of the Related Art
With recent advances in personal computers, especially portable personal computers, the demand tends to arise for liquid crystal displays, especially color liquid crystal displays. However, in order to further popularize the use of liquid crystal displays, a reduction in cost must be achieved. Especially, it is required to reduce the cost of a color filter which occupies a large proportion of the total cost. Various methods have been tried to satisfy the required characteristics of color filters while meeting the above requirements. However, any method capable of satisfying all the requirements has not been established. The respective methods will be described below.
The first method is a pigment dispersion method, which is currently replacing a dyeing method. In this method, a pigment-dispersed photosensitive resin layer is formed on a substrate and patterned into a single-color pattern. This process is repeated three times to obtain R, G, and B color filter layers.
The second method is the dyeing method. In the dyeing method, a water-soluble polymer material as a dyeable material is coated on a glass substrate, and the coating is patterned into a desired shape by a photolithography process. The obtained pattern is dipped in a dye bath to obtain a colored pattern. This process is repeated three times to form R, G, and B color filter layers.
The third method is an electrodeposition method. In this method, a transparent electrode is patterned on a substrate, and the resultant structure is dipped in an electrodeposition coating fluid containing a pigment, a resin, an electrolyte, and the like to be colored in the first color by electrodeposition. This process is repeated three times to form R, G, and B color filter layers. Finally, these layers are calcined.
The fourth method is a print method. In this method, a pigment is dispersed in a thermosetting resin, a print operation is performed three times to form R, G, and B coatings separately, and the resins are thermoset, thereby forming colored layers. In either of the above methods, a protective layer is generally formed on the colored layers.
The point common to these methods is that the same process must be repeated three times to obtain layers colored in three colors, i.e., R, G, and B. This causes an increase in cost. In addition, as the number of processes increases, the yield decreases. In the electrodeposition method, limitations are imposed on pattern shapes which can be formed. For this reason, with the existing techniques, it is difficult to apply this method to TFTs. In the print method, a pattern with a fine pitch is difficult to form because of poor resolution and poor evenness.
In order to eliminate these drawbacks, methods of manufacturing color filters by an ink-jet system are disclosed in Japanese Patent Laid-Open Nos. 59-75205, 63-235901, and 1-217320. In these methods, coloring solutions containing coloring agents of three colors, i.e., R (red), G (green), and B (blue), are sprayed on a transparent substrate by an ink-jet system, and the respective coloring solutions are dried to form colored image portions. In such an ink-jet system, R, G, and B filter elements (pixels) can be formed at once, allowing great simplification of the manufacturing process and a great reduction in cost.
In a color filter used for a general liquid crystal display device or the like, the opening portions (i.e., pixels) of the black matrix which partition off the respective pixels are rectangular, whereas the shapes of inks discharged from ink-jet heads are almost spherical. It is therefore difficult to discharge a required amount of ink for one pixel at once and uniformly spread the ink over the entire opening portion of the black matrix. For this reason, a plurality of inks are discharged onto each pixel while the ink-jet head is scanned with respect to the substrate, thereby coloring each pixel. In this case, if a plurality of inks are simply discharged into each pixel by one scanning operation, the respective pixels are difficult to color uniformly.
The present invention has been, therefore, made in consideration of the above problems, and has as its object to provide a color filter manufacturing method and apparatus which can manufacture a high-quality color filter by greatly reducing color irregularity in the respective pixels.
It is another object of the present invention to provide a color filter manufactured by the above manufacturing method and apparatus, a display device using the color filter, and an apparatus having the display device.
In order to solve the above problems and achieve the above objects, according to the present invention, there is provided a method of manufacturing a color filter by coloring each pixel with a plurality of discharged inks arrayed in a scanning direction while relatively scanning an ink-jet head over a substrate a plurality of numbers of times, comprising performing a coloring operation while changing discharging positions of inks onto the respective pixels in at least one of a plurality of scanning operations with respect to those in other scanning operations.
According to the present invention, there is provided an apparatus for manufacturing a color filter by coloring each pixel with a plurality of discharged inks arrayed in a scanning direction while relatively scanning an ink-jet head over a substrate a plurality of numbers of times, comprising control means for controlling the ink-jet head to perform a coloring operation while changing discharging positions of inks onto the respective pixels in at least one of a plurality of scanning operations with respect to those in other scanning operations.
In addition, according to the present invention, there is provided a color filter manufactured by coloring each pixel with a plurality of discharged inks arrayed in a scanning direction while relatively scanning an ink-jet head over a substrate a plurality of numbers of times, wherein a coloring operation is performed while discharging positions of inks onto the respective pixels in at least one of a plurality of scanning operations are changed with respect to those in other scanning operations.
Furthermore, according to the present invention, there is provided a display device having a color filter manufactured by coloring each pixel with a plurality of discharged inks arrayed in a scanning direction while relatively scanning an ink-jet head over a substrate a plurality of numbers of times, integrally comprising a color filter colored by changing discharging positions of inks onto the respective pixels in at least one of a plurality of scanning operations with respect to those in other scanning operations, and light amount changing means for changing a light amount.
According to the present invention, there is provided an apparatus including a display device having a color filter manufactured by coloring each pixel with a plurality of discharged inks arrayed in a scanning direction while relatively scanning an ink-jet head over a substrate a plurality of numbers of times, integrally comprising a display device integrally including a color filter colored by changing discharging positions of inks onto the respective pixels in at least one of a plurality of scanning operations with respect to those in other scanning operations, and light amount changing means for changing a light amount, and image signal supply means for supplying an image signal to the display device.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.